JPS6379023A - Temperature sensor - Google Patents

Abstract

PURPOSE:To enable production simple with high yields, by a method wherein a p-n junction characteristic is obtained with a diode and a semiconductor characteristic resembling metal characteristic with a resistor and both the components are connected in series to secure a necessary characteristic as temperature sensor. CONSTITUTION:In this sensor, a diode 1 with the forward voltage drop depending on temperature and a resistor 2 with the resistance sharply changing in a specified low-temperature area are connected in series. In the sensor thus arranged, rectification characteristic based on a p-n junction and a Schottkey junction is realized with the diode 1 which semiconductor characteristic resembling metal characteristic with the resistance sharply increasing in a low- temperature area is implementel by the resistor 2. This provides an area with a relatively small voltage drop dependency on the temperature and an area with a relatively large voltage drop dependency thereon with a specified low- temperature area as interface by connecting both the components directly.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a temperature sensor, and more particularly, to a temperature sensor that uses a diode to measure the temperature in a low temperature region.

<Prior Art> It has been known that the temperature in a low temperature region can be measured by passing a constant current through a pn junction diode and detecting the voltage between the terminals of the diode in this state.

To explain in more detail, the temperature dependence of the forward voltage drop of a diode is dV, /ciT-V/'r-(kT/q)d/dT(I
nIO) (where k is the Boltzmann constant, q is the absolute value of the electron charge, ■0 is the reverse saturation current, ■ is the forward drop voltage, and T is the absolute temperature).

According to the above equation, the forward drop voltage of the diode varies linearly depending on the absolute temperature, but the actually detected terminal voltage shows a sudden change near 25', for example. It is known that.

Therefore, with the temperature that shows the above rapid change as the boundary,
Highly accurate temperature measurements can be made on the low temperature side, and less accurate temperature measurements can be made on the high temperature side (M, G, Rao.

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The reason why the forward voltage drop changes rapidly as described above is that the substrate resistance constituting the diode has temperature dependence, and the substrate resistance increases as the temperature decreases. In other words, the forward voltage drop at the pn junction shows a change based on the above formula even in the low temperature range, but the substrate resistance is negligibly small compared to the forward voltage drop in the normal temperature range. This is due to the fact that in the low-temperature region, the lateral base becomes so large that it cannot be ignored.

<Problems to be Solved by the Invention> The temperature sensor having the above configuration uses a diode that has a pn junction and has semiconductor characteristics similar to so-called metal characteristics, in which the substrate resistance increases rapidly only in a low temperature region. Accurate temperature measurement in low-temperature ranges is possible only by using diodes with both of the above characteristics, which makes it difficult to manufacture usable diodes and reduces product yield. Furthermore, since the temperature at which the inter-terminal voltage rapidly changes is fixed at one point, there is a problem that the low temperature region in which temperature measurement can be performed with high accuracy is limited. In other words, it is necessary to simultaneously form a region consisting of a pn junction and a region with an impurity concentration that exhibits semiconductor characteristics close to metal characteristics inside one diode, but if the impurity concentration is incorrectly controlled, either one of the characteristics may change. Only the area showing the value will be formed. As a result, as mentioned above, manufacturing becomes difficult and the yield of the product decreases.

Therefore, it is impossible to measure temperature over a wide range from room temperature to extremely low temperatures using a temperature sensor using a diode, for example, when detecting the temperature of a cryopump.

<Object of the invention> This invention was made in view of the above problems,
It is an object of the present invention to provide a temperature sensor that can be easily manufactured with a high yield and that can easily cope with changes in the temperature range to be measured.

Means for Solving the Problems> To achieve the above object, the temperature sensor of the present invention comprises a diode whose forward voltage drop is temperature dependent, and a diode whose resistance is low in a predetermined low temperature region. It is connected in series with a rapidly changing resistor.

However, a plurality of resistors having different low-temperature regions where the resistance rapidly changes may be selectively connected in series with a diode.

In the temperature sensor with the above configuration, the rectifying characteristics based on the pn junction and Schottky junction are realized by the diode, and the semiconductor characteristics, which are close to metal characteristics, where the resistance value increases rapidly in the low temperature region, are realized by the resistor. Therefore, when both are connected in series, it is possible to have a region where the temperature dependence of the voltage drop is relatively small and a region where the temperature dependence of the voltage drop is large, with a predetermined low temperature region as the boundary. can.

Furthermore, if the low-temperature region where the resistance changes rapidly is made up of several different resistors selectively connected in series with a diode, the voltage can be reduced by simply changing the resistor connected in series with the diode. It is possible to change the low temperature region where the drop changes rapidly.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

Figure 1 is an electric circuit diagram showing the principle of the temperature sensor of the present invention, in which a diode (1) and a resistor (2) are connected in series, and a constant current source (3) is connected in the forward direction. Furthermore, a voltmeter (4) is connected between the terminals of the series connection portion of the diode (1) and the resistor (2).

Note that the diode (1) may be any diode having a pn junction or a Schottky junction, and a substrate having no semiconductor characteristics close to metal characteristics may be used. Further, the resistor [2] may be any material that has semiconductor characteristics similar to metal characteristics in which the resistance value increases rapidly depending on the temperature only in a low temperature region.

In the temperature sensor with the above configuration, as shown in Fig. 2A, the diode (1) can obtain a semiconductor characteristic in which the voltage drop changes smoothly and linearly over a wide temperature range, and as shown in Fig. 2B. As shown in the figure, the resistor (a
It can be obtained by

Therefore, the characteristics obtained by the series connection circuit of the diode (1) and the resistor (2), as shown in Figure 2C, decrease in a gentle straight line on the high temperature side, with a predetermined temperature range as the boundary. The voltage changes, and the voltage drop suddenly changes on the low temperature side.

Then, the temperature can be measured by measuring the voltage drop using the voltmeter [4] based on this characteristic and converting it based on the characteristic curve shown in FIG. 2C.

Note that the characteristic curve shown in Figure 2C can be easily changed by replacing only the resistor (2).
By preparing many types of resistors (2), temperature measurements over a wide range can be performed.

3 to 6 are side views showing specific examples.

In the specific example shown in FIG. 3, a resistor (2) made of Ge is attached to the top surface of the sample stage (6) to which a lead wire (5) is attached, and a diode made of 81 is attached to the top surface of the resistor (2). (1) and connect the above lead wire (
5) to supply a constant current.

FIG. 4 is a side view showing another specific example, in which the sample stage (6)
A resistor (2) made of Ge and a diode (1) made of 81 are attached to the top surface, and a lead wire (7) connects them, and a constant current is supplied through the lead wire (5). I try to do that.

FIG. 5 is a side view showing still another specific example, in which a diode (1) consisting of 81 is attached to the top surface of the sample stage (6), and a resistor consisting of 81 is attached to the top surface of the diode (1). '2J is attached, and a constant current is supplied to both through the lead wire [5].

FIG. 6 is an electric circuit diagram showing another embodiment, and FIG. 7 is a perspective view showing a specific example. The difference from the above embodiment is that three resistors (21), (22), and Each diode
1' (connected in series with 13, and selector switch (8) to selectively connect constant current source [3) to either resistor.
It is only the points that are connected.

Therefore, in the case of this embodiment, the changeover switch [8
By scanning the constant current source [3] and changing the resistor connected to the constant current source [3], it is possible to select one of the three characteristic curves shown in Fig. 8, resulting in high accuracy. The low temperature range in which temperature measurements can be made can be easily changed.

In the case of this embodiment, it is sufficient to change the display scale of the display (not shown) that displays the temperature in accordance with the selection of the resistor, but instead of switching the display scale,
The voltage may be increased by a predetermined amount, or a correction calculation may be performed by a microcomputer. <Effects of the Invention> As described above, the present invention obtains p-n junction characteristics using a diode, and obtains characteristics close to metals using a resistor. By obtaining semiconductor characteristics and connecting the two in series, the characteristics necessary for a temperature sensor are obtained, which simplifies manufacturing and improves product yield.Furthermore, the temperature measurement range is It has the unique effect of being able to easily make changes.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing the principle of this invention, Fig. 2 is a diagram showing characteristic curves, Figs. 3 to 5 are side views showing specific examples, and Fig. 6 shows an embodiment of a pond. An electric circuit diagram, FIG. 7 is a perspective view showing a specific example, and FIG. 8 is a diagram showing a characteristic curve. (1)...Diode, (2)...Resistor, (3)
... Constant current source, (4) ... Voltmeter Patent applicant Daikin Industries, Ltd. Figure 1 Figure 8 Temperature + Kl Award 'I'> Idyl

Claims (2)

[Claims] 1. A temperature sensor comprising a diode whose forward voltage drop is temperature dependent and a resistor whose resistance rapidly changes in a predetermined low temperature region are connected in series. 2. 2. The temperature sensor according to claim 1, wherein a plurality of resistors having different low temperature regions where resistance rapidly changes are selectively connected in series with diodes.